빙-구조물 상호작용의 동적거동해석

임채환(Chae Whan Rim),이종원(Jong Won Lee),신병천(Byung Chun Shin) 대한조선학회 1996 대한조선학회 논문집 Vol.33 No.4

쇄빙 과학조사선 선수부에 작용하는 빙하중 추정

임채환(Chae-Whan Rim),이탁기(Tak-Kee Lee) 대한조선학회 2007 대한조선학회 논문집 Vol.44 No.5

DAFUL과 Aerodyn을 활용한 풍력발전시스템의 동적거동 시뮬레이션 기술 개발

임채환(Chae Whan Rim),방제성(Je Sung Bang),문석준(Seok Jun Moon),정태영(Tae Young Chung),조희제(Huije Cho) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.5

Simulation technology for dynamic analysis of wind turbine is developed. The Aerodyn and the DAFUL are chosen for aerodynamic analysis and multi-body and flexible body dynamics respectively. Subroutines and variables of Aerodyn developed by NREL are analyzed with hub-height wind data, full field turbulent wind data and Airfoil data. The interface to perform coupled analysis between AeroDyn and DAFUL, GUI for modeling several parts of wind turbines are developed. The program will be extended to analyze the coupled analysis of aerodynamic and hydrodynamic behavior for floating offshore wind turbines.

Development of Aerodynamic Analysis Technology for Wind Turbines using a Multibody Dynamic Analysis Software

임채환(Rim, Chae Whan),방제성(Bang, Je Sung),조희제(Cho, Huije),문석준(Moon, Seok Jun),정태영(Chung, Tae Young) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06

Simulation technology for dynamic analysis of wind turbine is developed. The Aerodyn and the DAFUL are chosen for aerodynamic analysis and multi-body and flexible body dynamics respectively. Subroutines and variables of Aerodyn developed by NREL are analyzed with hub-height wind data, full field turbulent wind data and Airfoil data. The interface to perform coupled analysis between AeroDyn and DAFUL, GUI for modeling several parts of wind turbines are developed. The program will be extended to analyze the coupled analysis of aerodynamic and hydrodynamic behavior for floating offshore wind turbines.

용접부 잔류응력 추정기법 개발

임채환(Chae Whan Rim),윤병현(Byung Hyun Yun),박성환(Seong Whan Park) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.8

To estimate welding residual stress distribution, measurement and calculation were done for 2 types of model, thin and thick plates. The residual stress around the welding bead was measured with Barkhausen method. For the numerical calculation commercial program ANSYS was used. The results of measurement and calculation show that Satoh's formula for calculating residual stress of butt weld estimates longer distance of the location of maximum compressive stress and wider range of residual stress zone. According to the results a formula modifying Satoh's for estimating the residual stress of butt welding was proposed.

On the prediction of global first-year ice loads

Chae-Whan Rim(임채환) 한국해양공학회 1997 한국해양공학회지 Vol.11 No.3

A model and associated computer program was developed for a deterministic prediction of global first-year ice loads on offshore structures. The load caused by a ridge consists of load components arising from a consolidated layer, a rubble pile that develops in front of the structure and of the ridge keel. The ridge keel is considered as a layered accumulation of ice rubble, below the consolidated layer. The uppermost layer of the ridge keel can have a high apparent cohesion strength, due to ice blocks that are partially frozen into the consolidated layer.<br/> A soil mechanical approach is used to simulate the changes in the keel profile when a structure penetrates the ridge. Both vertical and inclined structures can be considered by the present model.<br/> A parametric study was made to determine how some of the uncertainties of the input parameters influence the global load evaluation. Therefore, it should be appreciated that the example calculations shown above do not represent actual ice load predictions for the example structure considered. It was found that the present lack of knowledge about the internal friction angle of the ridge keel represents a major source of uncertainty in ice load prediction. The computations also showed that the layered structure of the ridge keel may influence the keel load component considerably. The frictional resistance that develops at the rubble/structure contact area causes an increase in the ice load. The inclination of the structure has the same effect if the ice wall forces the ice rubble upwards during ridge penetration.

Effect on the Output Power by the Inner Radius of Wind Tower

Chae Whan Rim(임채환),Sang Kyu Choi(최상규),Jin Gyun Kim(김진균),Ju Seok Nam(남주석),Sung Gyoung Park(박성경),Soo Yong Cho(조수용) 한국신재생에너지학회 2015 한국신재생에너지학회 학술대회논문집 Vol.2015 No.6

초기 조건이 부유식 풍력터빈 동역학 해석의 과도응답에 미치는 영향

송진섭(Jin-Seop Song),임채환(Chae-Whan Rim),문석준(Seok-Jun Moon),남용윤(Yong-Yun Nam) 한국해양공학회 2014 한국해양공학회지 Vol.28 No.4

The IEC standard for onshore or offshore wind turbines requires additional dummy simulations (at least 5 s) for the transient responses due to initial conditions. An increase in the dummy time causes a considerable increase in the computational cost considering multiple design spirals with several thousand design load analysis cases. A time of 30 s is typically used in practical simulations for a wind turbine design with a fixed platform. However, 30 s may be insufficient for floating offshore wind turbines (FOWT) because the platforms have lower natural frequencies, and the transient responses will last much longer. In this paper, an initial condition application algorithm is implemented for Wind Hydro, and the appropriate dummy simulation time is investigated based on a series of dynamic simulations of a FOWT. As a result, it is found that more than 300 s is required for the platform to have stationary motion after the initial transient responses for the FOWT under the conditions considered.

수직축 풍력터빈 성능향상을 위한 풍력타워 최적설계에 관한 연구

조수용(Soo-Yong Cho),임채환(Chae Hwan Rim),조종현(Chong-Hyun Cho) 한국항공우주학회 2019 한국항공우주학회지 Vol.47 No.3

풍력 타워는 수직형 풍력터빈의 성능을 향상시키기 위해 사용되어왔다. 하지만 올바르게 설계되지 않은 풍력 타워는 오히려 풍력터빈의 성능을 저하시킬 수 있다. 따라서 본 연구에서는 풍력 타워의 최적화 연구를 수행하였다. 이를 위하여 다음과 같이 6가지의 설계변수가 선택되었다. 즉, 가이드 벽의 외부 및 내부 반경, 스플리터의 적용 여부, 스플리터의 내부 반경, 가이드 벽의 개수 및 원주각도가 선정되었다. 최적화를 위한 목적함수는 풍력타워 내에 설치된 수직형 풍력터빈에서의 주기적인 평균 토크가 사용되었으며, 최적화 과정에서 지엽적인 최적화 결과를 피하기 위하여 실험계획법, 유전자알고리즘 및 인공신경망기법이 사용되었다. 인공신경망은 세대의 증가에 따라 지속적으로 향상하였으며, 수직 풍력터빈의 성능은 독립운전에 비하여 최적화된 풍력 타워 내에서 두 배 이상 향상되었다. Wind power tower has been used to augment the performance of VAWT (Vertical Axis Wind Turbine). However, inappropriately designed wind power tower could reduce the performance of VAWT. Hence, an optimization study was conducted on a wind power tower. Six design variables were selected, such as the outer radius and the inner radius of the guide wall, the adoption of the splitter, the inner radius of the splitter, the number of the guide wall and the circumferential angle. For the objective function, the periodic averaged torque obtained at the VAWT was selected. In the optimization, Design of Experiment (DOE), Genetic Algorithm (GA), and Artificial Neural Network (ANN) have been applied in order to avoid a localized optimized result. The ANN has been continuously improved after finishing the optimization process at each generation. The performance of the VAWT was improved more than twice when it operated within the optimized wind power tower compared to that obtained at a standalone.

Introduction to the NREL Design Codes for System Performance Test of Wind Turbines

방제성(Bang, Je-Sung),임채환(Rim, Chae Whan),정태영(Chung, Tae Young) 한국신재생에너지학회 2011 한국신재생에너지학회 학술대회논문집 Vol.2011 No.11

NREL NWTC Deside codes are analyzed and introduced to develop the system performance simulation program for wind turbine generator systems. In this paper, The FAST performing multi-body and flexible body dynamics, control and the AeroDyn calculating aerodynamic forces with airfoil data and wind data are explained. Furthermore, initialization and process for transfer of aerodynamic force between AeroDyn and FAST at each time step are also introduced.